U.S. patent number 7,650,127 [Application Number 11/284,462] was granted by the patent office on 2010-01-19 for gain controlled external low noise amplifier.
This patent grant is currently assigned to Continental Automotive Systems US, Inc.. Invention is credited to Josef Baumgartner, Nahel Eshaq, Brian Marlett.
United States Patent |
7,650,127 |
Baumgartner , et
al. |
January 19, 2010 |
**Please see images for:
( Certificate of Correction ) ** |
Gain controlled external low noise amplifier
Abstract
A receiver for receiving radio frequency signals from a remote
keyless entry system and another system includes a low noise
amplifier for amplifying and increasing the range and sensitivity
of the receiver, such that the receiver may receive signals at
increased distances. A gain of the low noise amplifier is
selectively controlled to cycle from a first gain level that
provides for increased sensitivity and a second gain level that
provides a lower sensitivity and a greater dynamic range or larger
signal capacity.
Inventors: |
Baumgartner; Josef (Vienna,
AT), Eshaq; Nahel (Warren, MI), Marlett; Brian
(Macomb, MI) |
Assignee: |
Continental Automotive Systems US,
Inc. (Auburn Hills, MI)
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Family
ID: |
36653909 |
Appl.
No.: |
11/284,462 |
Filed: |
November 21, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060154634 A1 |
Jul 13, 2006 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60642724 |
Jan 10, 2005 |
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Current U.S.
Class: |
455/234.1;
455/245.1 |
Current CPC
Class: |
H04B
1/18 (20130101); H04B 1/109 (20130101) |
Current International
Class: |
H04B
1/06 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Le; Thanh C
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to U.S. Provisional Application
No. 60/642,724, which was filed on Jan. 10, 2005.
Claims
What is claimed is:
1. A method of operating a receiver comprising the steps of: a)
searching for one of at least two possible incoming signals with a
low noise amplifier of a receiver; b) receiving a signal from a
remote keyless entry system and at least one other system c)
cycling a gain provided by the low noise amplifier between a high
value and a low value at a desired time interval; and d)
automatically adjusting the gain provided by the low noise
amplifier to the low value responsive to a triggering event.
2. The method as recited in claim 1, including triggering a
reduction in a gain provided by the low noise amplifier responsive
to receiving a signal from the at least one other system.
3. The method as recited in claim 1, including adjusting the gain
of the low noise amplifier responsive to a signal strength received
above a desired threshold value.
4. The method as recited in claim 3, including utilizing a received
signal strength indicator of the receiver to control the low noise
amplifier.
5. The method are recited in claim 1, wherein the at least one
other system comprises a tire pressure monitoring system disposed
on a motor vehicle.
6. The method as recited in claim 5, including triggering a
reduction in gain of the low noise amplifier responsive to opening
of a door to the motor vehicle.
7. A method of operating a receiver for a remote keyless entry
system and at least one other system comprising the steps of: a)
amplifying an incoming signal from a remote transmitter to improve
an effective operational range of the receiver with a low noise
amplifier; b) sensing a signal strength with a signal strength
indicator within the receiver; and c) reducing amplification
provided by the low noise amplifier from a first level to a second
lower level responsive to a triggering event, wherein the
triggering event is indicative of the remote transmitter being
within a range not requiring the improved effective operational
range of the receiver.
8. The method as recited in claim 7, wherein the triggering event
comprises receiving a signal greater than a desired threshold
value.
9. The method as recited in claim 8, wherein the triggering event
comprises opening of an entry door to a motor vehicle.
10. The method as recited in claim 8, wherein the triggering event
comprise receipt of a signal from the remote transmitter greater
than a desired threshold value.
11. The method as recited in claim 8, including the step of cycling
between a first high amplification level and a second low
amplification level.
12. A receiver for a remote keyless entry system of a motor vehicle
comprising: a low noise amplifier for amplifying an incoming
signal; a signal strength indicator for measuring a strength of the
incoming signal; and a controller for adjusting a level of gain for
the amplification of an incoming signal responsive to a triggering
event indicative of an expected increase in signal strength from an
incoming signal from the remote keyless entry system, wherein the
receiver receives signals from the remote keyless entry system and
at least one other system.
13. The receiver as recited in claim 12, wherein the remote keyless
entry system includes a remote transmitter, and the low noise
amplifier increases an effective range of the remote transmitter.
Description
BACKGROUND OF THE INVENTION
This invention generally relates to a method and device for
receiving input signals with a receiver from multiple systems. More
particularly, this invention relates to a method of operating a low
noise amplifier for a receiver receiving input from multiple
systems.
A receiver for automotive system applications typically receives
signals for a remote keyless entry system. In many instances it is
desirable for the receiver to recognize and receive signals from a
remote transmitter at increased distances. An external low noise
amplifier (LNA) installed with the receiver provides increased
signal sensitivity that translates into the capability of receiving
signals from increased distances. The LNA provides an increased
gain to surrounding signals that increases the range and
sensitivity of the receiver.
Disadvantageously, the increased gain provided by the external LNA
reduces large signal capability and therefore increases the
probability that the receiver is blocked by an interfering signal.
Many receivers are utilized for multiple automotive systems such as
both a remote keyless entry system and a tire pressure monitoring
system. The signals from the tire pressure monitoring system do not
require amplification, as they are located on the vehicle. However,
external interference received by the receiver due to the increased
sensitivity provided by the LNA system could cause undesirable
interference with such signals.
Accordingly, it is desirable to develop a method of controlling an
external low noise amplifier to provide the desired increase in
receiver range and sensitivity while also providing reliable
receipt of other signals.
SUMMARY OF THE INVENTION
An example receiver according to this invention includes an
external low noise amplifier that is controlled to operate between
a first high gain and a second lower gain.
An example receiver is provided for receiving a radio frequency
signal from a remote keyless entry (RKE) system and another system.
The receiver includes a low noise amplifier for amplifying and
increasing the range and sensitivity of the receiver, such that the
receiver may receive signals at increased distances. A gain of the
low noise amplifier is adjusted in view of a signal strength
measured by a received signal strength indicator. The low noise
amplifier increases the sensitivity of the receiver to external
signals, providing for weaker signals to be received and
recognized.
The low noise amplifier is selectively controlled to cycle from a
first gain level that provides for increased sensitivity and a
second gain level that provides a lower sensitivity and a greater
dynamic range or large signal capacity. Cycling between the first
gain level and the second gain level occurs responsive to a
triggering event.
Accordingly, the method and device according to this invention
controls the gain level of the external low noise amplifier to
increase receiver sensitivity and thereby remote transmitter range,
while maintaining reliable operation and large signal
capability.
These and other features of the present invention can be best
understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a vehicle including an
example receiver and low noise amplifier according to this
invention.
FIG. 2 is a block diagram illustrating example method steps
according to this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a motor vehicle 10 includes a remote keyless
entry system (RKE) 12 and a tire pressure monitoring (TPM) system
14. A receiver 16 is provided for receiving radio frequency signals
from both the RKE system 12 and the TPM system 14. The receiver 16
includes an external low noise amplifier 18 for amplifying and
increasing the range and sensitivity of the receiver 16, such that
the receiver 16 may receive signals at increased distances. A gain
of the low noise amplifier 18 can be adjusted according to a
measured signal strength measured by a received signal strength
indicator 20 that is integral with the receiver 16.
The RKE system 12 includes a remote transmitter 26 that transmits a
signal 28. A distance at which the signal 28 can be read between
the receiver 16 and the remote transmitter 26 is increased by the
externally mounted low noise amplifier 18. The low noise amplifier
18 increases the sensitivity of the receiver 16 to external
signals, providing for weaker signals to be received and
recognized. Receiving weaker signals provides for receipt of RKE
signals 28 at an increased distance. This provides a desirable
increase in range at which signal from the remote transmitter 26
are recognized and acted on by the RKE system 12 of the vehicle
10.
Unfortunately, the increase in sensitivity provided by the low
noise amplifier 18 also results in a decrease in the large signal
capability of the receiver 16. The addition of the external low
noise amplifier 18 decreases the dynamic range of the receiver 16.
As a result interfering external signals can easily block the
receiver thus decreasing the range at which wanted signals can be
received to zero.
In the example vehicle 10 the increase in gain provided by the low
noise amplifier 18 increases the range at which the RKE signal 28
can be received, but can in some instances result in the inability
to receive a TPM signal 30 emitted by individual TPM sensors 24
installed on the vehicle 10. The low noise amplifier 18 is
therefore controlled to cycle between a first gain level that
increases the range at which the RKE signal 28 can be received and
a second gain lower than the first gain level to provide for
receipt of TPM signals 30. Although an RKE signal and a TPM signal
are discussed and illustrated as examples, receivers that receive
signals for other systems will benefit from this invention, and one
knowledgeable in the art will recognize that other such systems are
within the contemplation of this invention.
The example receiver 16 is disposed as part of an integrated
circuit 22 and includes a received signal strength indicator 20.
The received signal strength indicator 20 provides information to
the integrated circuit 22 indicative of signal strength. A signal
from the received signal strength indicator 20 is low pass filtered
to provide time averaging. This information is then utilized to
control the gain level for the low noise amplifier 18.
The low noise amplifier 18 is selectively controlled to cycle from
a first gain level that provides for increased sensitivity and a
second gain level that provides a lower sensitivity and a greater
dynamic range or large signal capacity. Cycling between the first
gain level and the second gain level occurs responsive to a
triggering event. The triggering event can be a positive activation
such as the opening of a car door, or insertion of a key into the
ignition. Such events indicate that an operator is within or very
near the vehicle and therefore increased range is not required. The
gain provided by the low noise amplifier 18 can therefore be
reduced to the second lower level to provide reliable receipt of
signals such as the TPM signals 30.
The triggering event may also comprise a signal strength received
from the remote transmitter 26. As appreciated, as the remote
transmitter 26 is moved closer to the receiver, the measured signal
strength as is received by the received signal strength indicator
20 increases. After obtaining a desired signal strength threshold
value, the low noise amplifier 18 is switched to the lower gain
level. As should be understood, a number of ways of triggering
cycling between gain levels of the low noise amplifier are within
the contemplation of this invention.
Referring to FIG. 2, operation of the receiver 18 is schematically
illustrated by block diagram 40 and includes the amplification of
incoming signals according to a first gain level provided by the
low noise amplifier 18 as is indicated at 42. The amplified
incoming signal is sent to the receiver 16 and the strength of that
signal noted as is indicated at 44. The receiver 16 is adapted to
receive signals from at least two different systems. As
appreciated, of the at least two systems, only the RKE system 12
requires signal amplification for improved operation. Other systems
disposed on the vehicle 10 such as the TPM system 14 operates as
desired without significant signal amplification.
The gain of the low noise amplifier 18 can either be selectively
adjusted to a lower second gain level responsive to a triggering
event as is indicated at 48 or cycled between the first higher gain
level and the lower second gain level responsive to a specific time
interval. Further, the low noise amplifier 18 may be operated
utilizing a combination of cycling and switching responsive to the
received signal strength. As appreciated, the receiver 16 can be
cycled between first and second gain levels at specified time
intervals, and then switched to the low gain level responsive to a
triggering event such as the receipt of a signal above a desired
strength.
Once the low gain level is selected another event such as a lapse
of time or an exit from the vehicle indicated by the vehicle being
turned off, the low noise amplifier 18 can be cycled back to the
first higher gain level as is indicated at 50. Operation would then
repeat the method steps as indicated at 52 until another triggering
event or expiration of a desired time interval.
Accordingly, the method and device according to this invention
controls the gain level of the external low noise amplifier 18 to
increase receiver sensitivity and thereby remote transmitter range,
while maintaining reliable operation and large signal
capability.
Although a preferred embodiment of this invention has been
disclosed, a worker of ordinary skill in this art would recognize
that certain modifications would come within the scope of this
invention. For that reason, the following claims should be studied
to determine the true scope and content of this invention.
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